Rooftop curable heat seamable roof sheeting and method for covering roofs

ABSTRACT

A rooftop curable heat seamable sheet material for roofing prepared from an uncured polymeric composition of matter comprises a semi-crystalline polymer having more than about 2 percent by weight crystallinity and selected from the group consisting of polyolefins prepared from monomers containing at least 2 carbon atoms, a filler selected from the group consisting of reinforcing and non-reinforcing materials and mixtures a processing material or mixtures thereof; and a cure package capable of allowing the composition of matter to cure at temperatures of at least about 50° C. A method for covering a roof is also provided and comprises the steps of applying layers of rooftop curable sheet material prepared from said uncured heat seamable polymeric composition of matter to the roof being covered; overlapping adjacent edges of the layers; and seaming the overlapping areas under sufficient heat and some pressure to provide acceptable seam strength, the composition of matter being curable at temperatures of at least about 50° C.

TECHNICAL FIELD

The present invention relates generally to sheeting material used forroofing. More particularly the sheeting material is comprised ofethylene-propylenediene terpolymer, referred to herein as EPDM,ethylene-propylene rubber, referred to herein as EPR, ethylene-butenecopolymer, ethylene-octene copolymer or similar olefinic type polymer,and mixtures thereof. The roof sheeting material of the presentinvention is curable at relatively low temperatures of between 50° C.and 70° C. and is thus, rooftop curable, thereby effecting the cost oflabor and energy to cure the material. Moreover, being rooftop curable,it is not necessary to cure the material prior to installation whichotherwise effects a significant decrease in tack, necessitating the useof adhesives along the seams. A method is also provided for coveringroofs which includes the step of employing a rooftop curable sheetingmaterial of the present invention.

BACKGROUND OF THE INVENTION

Polymeric roof sheeting is used as single ply roofing membrane forcovering industrial and commercial flat roofs. Such membranes aregenerally applied to the roof surface in vulcanized or cured state. Asnoted hereinabove, energy is expended during the cure and it is likelythat an adhesive will be required to join adjacent seams of the materialduring installation.

Because of outstanding weathering resistance and flexibility, cured EPDMbased roof sheeting has been rapidly gaining acceptance. This materialnormally is prepared by vulcanizing the composition in the presence ofsulfur or sulfur containing compounds such as mercaptans. Our earlierU.S. Pat. No. 4,803,020 also teaches the use of radiation crosslinkingpromoters in an EPDM sheeting composition which can be cured by ionizingradiation.

Notwithstanding the usefulness of radiation curing and sulfur curing, adisadvantage of utilizing these elastomers is not only the lack ofadhesion of EPDM, especially cured EPDM, to itself but also the factthat the elastomer must be separately cured at some stage. The former isa serious problem because in applying EPDM sheets to a roof, it isusually necessary to splice the cured EPDM sheets together. This spliceor seam area is subjected to both short term and long term stresses suchas those caused by roof movement, heavy winds, freeze-thaw cycling andthermal cycling. Such stresses may manifest themselves in shear forcesor peel forces, i.e., the seam peels back under severe stress conditionsor results in a partially open seam (often referred to as a fish-mouthcondition) under less severe conditions.

In view of the foregoing problem, it has been necessary to utilize anadhesive to bond the cured EPDM sheets together. An adhesive for bondingcured EPDM elastomer roofing sheets together must meet a number ofrequirements which are extremely difficult to satisfy. Thus, theadhesive must provide sufficient peel and adhesive strength to permitthe splice formed by bonding the cured EPDM roofing sheets together toresist both the short term and long term stresses such as thosediscussed hereinabove. Moreover, the adhesive must be resistant tooxidation, hydrolysis and chemical attach from ponded water.Additionally, the adhesive must provide the important property oftenreferred to in the adhesive art as "Quick Stick". The term "Quick Stick"means the characteristics of two sheets of material which have beencoated with an adhesive composition to develop virtually immediateadhesive strength when placed in contact with each other.

Quick Stick is an extremely important property in an adhesive which isutilized to splice cured EPDM elastomer roofing sheets together. Thus,adhesive compositions presently known generally require anywhere fromabout two to about seven days at room temperature (i.e. 22° C.) toattain maximum adhesive strength. At higher ambient temperature, thistime period may be somewhat less but at minimum it will generally be atleast 24 hours. The conventional procedure for splicing the EPDM roofingsheets together is to make the splice within a relatively short periodof time after the adhesive coating has been applied to each sheet,generally within 30 minutes but often less. Accordingly, the adhesivecomposition must provide sufficient immediate adhesive strength or QuickStick to permit the splice to withstand stresses from winds, movement,handling by installers, etc. until the adhesive achieves its maximumstrength which as indicated will generally take from two to seven days.

Commercial contact adhesives which are conventionally employed forbonding cured EPDM elastomer roofing sheets together generally consistof solutions of neoprene or neoprene-type or butyl or butyl-typepolymers in aromatic or aromatic-aliphatic solvents containing2-butanone often along with tackifying resins. However, such adhesiveshave not proven to be very satisfactory due to their lower thandesirable peel adhesion strengths. Thus, the neoprene or butyl-typeadhesives often provide peel adhesion values at 22° C. of only 1 to 2pounds per linear inch.

Pressure sensitive and contact adhesive compositions containingneutralized, partially neutralized or unneutralized sulfonateelastomers, tackifying resins and organic solvents or organic solventmixtures are known in the prior art as shown by U.S. Pat. Nos. 3,801,531and 3,867,247.

U.S. Pat. No. 3,801,531 relates to pressure sensitive adhesivecompositions which contain thiouronium derivatives of unsaturatedelastomers or neutralized, partially neutralized or unneutralizedsulfonated elastomers including sulfonated EPDM, tackifying resinsincluding phenol formaldehyde or alkylphenol formaldehyde resins andorganic solvents or organic solvent mixtures including a preferred 90:10mixture of toluene and isopropyl alcohol. However, the patent does notdisclose or suggest the use of alkylphenols or ethoxylated alkylphenolsin such compositions.

U.S. Pat. No. 3,867,247 relates to adhesive contact cements whichcontain neutralized, partially neutralized or unneutralized sulfonatedbutyl elastomers, tackifying resins including phenol formaldehyde oralkylphenol formaldehyde resins and organic solvents or organic solventmixtures including a preferred 90:10 mixture of toluene and isopropylalcohol. However, the patent does not disclose or suggest the use ofalkylphenols or ethoxylated alkylphenols in such compositions.

The adhesive compositions described in the aforementioned patents sufferfrom a significant disadvantage which materially limits their usefulnessas a contact adhesive for bonding cured EPDM elastomer roofing sheetstogether and that is their deficiency in Quick Stick properties.

One such adhesive system for EPDM elastomers that provides good QuickStick is described in U.S. Pat. No. 4,480,012, owned by the Assignee ofrecord herein. Such adhesives comprise a neutralized sulfonated EPDMelastomeric terpolymer; an organic hydrocarbon; a para-alkylated phenolformaldehyde tackifying resin and an alkylphenol or ethoxylatedalkylphenol. While the use of such adhesive compositions is an effectivemeans of joining and sealing the edges of elastomeric roofing material,if the use of adhesives could be eliminated, the additional labormaterial costs and related hardware necessary to apply the adhesivewould effect a significant cost savings. Moreover, elimination of theneed to cure the material prior to its application to a roof would alsobe advantageous. Finally, elimination of the need to cure the sheetingmaterial at all would be a significant advantage over the use of knownmaterials.

SUMMARY OF THE INVENTION

It is thus an object of the present invention to provide rooftop curableheat seamable EPDM and EPR roof sheeting materials that need not beseparately subjected to cure prior to or subsequent to installation.

It is another object of the present invention to provide rooftop curableheat seamable EPDM and EPR roof sheeting materials which will show cureprogressing at temperatures readily obtainable on a black roofingmembrane exposed to sunlight in most climates.

It is still another object of the present invention to provide rooftopcurable heat seamable EPDM and EPR roof sheeting materials which willshow progressive increases in modulus and tensile strength attemperatures as low as 50° C.

It is yet object of the present invention to provide rooftop curableheat seamable EPDM and EPR roof sheeting materials which can be made tocure more rapidly or more slowly with minor compounding modifications.

It is still another object of the present invention to provide a methodfor covering roofs which employs rooftop curable heat seamable EPDM, EPRor other olefin type polymers as roof sheeting materials which do notrequire separate curing treatment prior to or subsequent toinstallation.

In general the present invention relates to a rooftop curable heatseamable sheet material for roofing prepared from an uncured polymericcomposition of matter comprising 100 parts by weight of asemi-crystalline polymer having more than about 2 percent by weightcrystallinity and selected from the group consisting of polyolefinsprepared from monomers containing at least 2 carbon atoms from about 20to 300 parts by weight of a filler selected from the group consisting ofreinforcing and non-reinforcing materials and mixtures thereof per 100parts of polymer; from about 20 to 150 parts by weight of a processingmaterial and mixtures thereof, per 100 parts of polymer; and from about1.5 to 10 parts by weight of a cure package capable of allowing thecomposition of matter to cure at temperatures of at least about 50° C.

A method for covering a roof is also provided and comprises the steps ofapplying layers of rooftop curable sheet material prepared from anuncured heat seamable polymeric composition of matter to the roof beingcovered; overlapping adjacent edges of the layers; and seaming theoverlapping areas under sufficient heat and pressure to provideacceptable seam strength, the composition of matter being curable attemperatures of at least about 50° C.

At least one or more of the foregoing objects, together with theadvantages thereof over the use of known rooftop sheeting materials,which shall become apparent to those skilled in the art, are describedin greater detail with reference to the specification which follows.

PREFERRED EMBODIMENT OF THE INVENTION

As noted hereinabove, the roof sheeting materials of the presentinvention comprise EPDM, EPR or other similar olefin type polymers. Theterm EPDM is used in the sense of its definition as found inASTM-D-1418-85 and is intended to mean a terpolymer of ethylene,propylene and a diene monomer with the residual unsaturation portion ofthe diene in the side chain. Illustrative methods for preparing suchterpolymers are found in U.S. Pat. No. 3,280,082 the disclosure of whichis incorporated herein by reference. The preferred polymers having fromabout 60 to about 95 weight percent ethylene and from about zero toabout 12 weight percent of the diene with the balance of the polymerbeing propylene or some other similar olefin type polymer.

The diene monomer utilized in forming the EPDM terpolymer is preferablya non-conjugated diene. Illustrative examples of non-conjugated dieneswhich may be employed are dicyclopentadiene, alkyldicyclopentadiene,1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-heptadiene,2-methyl-1,5-hexadiene, cyclooctadiene, 1,4-octadiene, 1,7-octadiene,5-ethylidene-2-norbornene, 5-n-propylidene-2-norbornene,5-(2-methyl-2-butenyl)-2-norbornene and the like. A typical EPDM isVistalon® MD-744 (Exxon Chemical Co.) a terpolymer having a MooneyViscosity (ML/4 at 125° C.) of about 52; an ethylene/propylene (E/P)ratio of 61/39 weight percent and 2.7 weight percent of unsaturation.

Particularly useful and preferred EPDM materials include Royalene® 375(Uniroyal Chemical Co.); and EPsyn® 5508 (Copolymer Rubber & ChemicalCorporation). Royalene 375 has a Mooney Viscosity (ML/4 at 125° C.) ofabout 50.8; an E/P ratio of 75/25 weight percent and about 2.0 weightpercent of unsaturation (dicyclopentadiene). EPsyn® 5508 has a MooneyViscosity (ML/4 at 125° C.) of about 55.6; and E/P ratio of 73/27 weightpercent and about 3.7 weight percent of unsaturation. An experimentalpolymer, EPsyn® DE-249 having a Mooney Viscosity (ML/4 at 125° C.) ofabout 56.1; an E/P ratio of 71/29 weight percent and about 1.7 weightpercent of unsaturation (5-ethylidene-2-norbornene) was also employed.

The term EPR is used in the sense of its definition as found in ASTMD-1418-85 and is intended to mean a copolymer of ethylene and propylene.The preferred copolymers contain from about 60 to 95 weight percentethylene with the balance to total 100 weight percent being propylene. Atypical EPR is Vistalon® 719 (Exxon Chemical Co.) having an E/P ratio ofabout 75/25 weight percent.

To be useful as a roofing material in the present invention it isnecessary that the EPDM have at least about 2 weight percentcrystallinity, from the ethylene component; an Mn as measured by GPC ofat least about 30,000 and an Mw, as measured by GPC of at least about100,000. Similarly, the EPR should have at least about 2 weight percentcrystallinity (ethylene); an Mn, as measured by GPC of at least about30,000 and an Mw, as measured by GPC of at least about 100,000. We havefound that the selection of an EPDM or EPR having high crystallinity (atleast 2 percent by weight) and a weight average molecular weight of atleast 100,000 is necessary to provide a roofing material which does notrequire curing prior to application, if ever, and which does not requireany type of adhesive, solvent-based or the like, to join and seam thespliced edges.

Also, useful as a roofing material in the present invention is acopolymer of ethylene and butene. This particular copolymer has about 82weight percent ethylene with the balance to total 100 weight percentbeing butene. A typical ethylene/butene copolymer is GERS-1085 (UnionCarbide Corporation) having an Mw, as measured by GPC of at least about221,000. Other similar olefinic polymers (e.g., ethylene/octenecopolymer) can be used to practice this invention. Generally speakingany semi-crystalline polymer having more than about 2 percent by weightcrystallinity and selected from the group consisting of polyolefinsprepared from monomers containing at least 2 carbon atoms can beemployed. For purposes of discussion herein, references to EPDM, EPR orsimilar olefinic polymers is intended to include any of thesemi-crystalline polymers of the present invention.

The composition or compound employed to form the roof sheeting materialcomprises 100 parts by weight of EPDM, EPR, or other similar olefinictype copolymers, including mixtures of two or more types, to which isadded basically fillers, and processing materials, a special curepackage and optionally, other components all of which are discussedhereinbelow.

With respect first to the filler, suitable fillers are selected from thegroup consisting of reinforcing and non-reinforcing materials, andmixtures thereof, as are customarily added to rubber. Examples includesuch materials as carbon black, ground coal, calcium carbonate, clay,silica, cryogenically ground rubber and the like. Generally, preferredfillers include carbon black, ground coal and cryogenically groundrubber.

Carbon black is used in an amount of about 20 parts to about 300 partsper 100 parts of polymer (phr), preferably in an amount of about 60 toabout 150 phr. The preferred range of carbon black herein (60 to 150phr) is about equal to the amount of carbon black normally used inpreparing sulfur cured EPDM roof sheeting. The carbon black usefulherein is any carbon black. Preferred are furnace blacks such as GPF(general purpose furnace), FEF (fast extrusion furnace) and SRF(semi-reinforcing furnace). These carbon blacks may also be blended withmore reinforcing blacks, i.e., HAF, ISAF, SAF and the like. For acomplete description of such carbon blacks, see for example, TheVanderbilt Rubber Handbook, pp 408-424, RT Vanderbilt Co., Norwalk,Conn. 06855 (1979).

The ground coal employed as a filler in the compositions of theinvention is a dry, finely divided black powder derived from a lowvolatile bituminous coal. The ground coal has a particle size rangingfrom a minimum of 0.26 microns to a maximum of 2.55 microns with theaverage particle size of 0.69±0.46 as determined on 50 particles usingTransmission Electron Microscopy. The ground coal produces an aqueousslurry having a pH of about 7.0 when tested in accordance with ASTMD-1512. A preferred ground coal of this type is designated Austin Blackwhich has a specific gravity of 1.22±0.03, an ash content of 4.58% and asulfur content of 0.65%. Austin Black is commercially available fromCoal Fillers, Inc., P.O. Box 1063, Bluefield, Va. Amounts range fromabout 5 to 65 phr with about 15 to 35 phr being preferred.

Finally, essentially any cryogenically ground rubber may be employed asa filler in the composition of the invention. The preferredcryogenically ground rubbers are cryogenically ground EPDM, butyl,neoprene and the like. A preferred cryogenically ground rubber is acryogenically ground EPDM rubber. The preferred cryogenically groundEPDM rubber is a fine black rubbery powder having a specific gravity of1.129±0.015 and a particle size ranging from about 30 to about 300microns with an average particle size ranging from about 50 to about 80microns. Amounts range from about 5 to 40 phr with about 10 to 25 phrbeing preferred.

Mixtures of Austin black and cryogenically ground rubber useful hereinmay be utilized as a partial replacement for carbon black. Wheremixtures of these two fillers are employed the relative amounts thereofcan be widely varied; the overall total not exceeding about 60 phr. Theratio of Austin black to cryogenically ground rubber may range from adesired ratio of 2:1 to perhaps even a ratio of 3:1. Again, as notedhereinabove, other filler materials can be employed. Amounts thereoffall within the range of amounts normally employed in preparing sulfurcured conventional roof sheeting.

With respect to the processing material, it is included to improve theprocessing behavior of the composition (i.e. reduce mixing time andincrease rate of sheet forming and includes processing oils, waxes andthe like). The processing oil is included in an amount ranging fromabout 20 parts to about 150 parts process oil per 100 parts EPDM or EPR,preferably in an amount ranging from about 60 parts to about 100 phr. Apreferred processing oil is a paraffinic oil, e.g. Sunpar 2280 which isavailable from the Sun Oil Company. Other petroleum derived oilsincluding naphthenic oils may be used.

Regarding the cure package, sulfur or sulfur vulcanizing agents ormixtures thereof employed in the rooftop curable membrane compositionmay range from about 1.5 phr to as high as 10 phr by weight with thepreferred amounts ranging from about 1.5 to about 6 phr. Sulfur isemployed in amounts of about 0.25 to 2 phr. In addition, the curepackage provides one or more vulcanizing accelerators includingthioureas such as ethylene thiourea; N,N-dibutylthiourea;N,N-diethylthiourea and the like; thiuram monosulfides and disulfidessuch as tetramethylthiuram monosulfide (TMTMS); tetrabutylthiuramdisulfide (TBTMS); tetramethylthiuram disulfide (TMTDS);tetraethylthiuram monosulfide (TETDS); and the like; benzothiazolesulfenamides such as N-oxydiethylene-2-benzothiazole sulfenamide;N-cyclohexyl-2-benzothiazole sulfenamide;N,N-diisopropyl-2-benzothiazole sulfenamide;N-tert-butyl-2-benzothiazole sulfenamide and the like;2-mercaptoimidazoline; N,N-diphenyl-guanadine;N,N-di-(2-methylphenyl)guanadine; 2-mercaptobenzothiazole;2-(morpholinodithio)-benzothiazole disulfide; zinc2-mercaptobenzothiazole and the like; dithiocarbamates such as telluriumdiethyldithiocarbamate; copper dimethyldithiocarbamate; bismuthdimethyldithiocarbamate; cadmium diethyldithiocarbamate; leaddimethyldithiocarbamate; zinc diethyldithiocarbamate and zincdimethyldithiocarbamate.

It should be appreciated that the foregoing list is not exclusive, andthat other vulcanizing agents known in the art to be effective in thecuring of EPDM terpolymers may also be utilized. For a list ofadditional vulcanizing agents, see The Vanderbilt Rubber Handbook,referenced hereinabove. Amounts of the various components that can beemployed in the cure package are set forth in Table I hereinbelow whichprovides both broad and preferred ranges for each type of component,when present. Again, the total amount of the cure package employedranges between about 1.5 and 10 phr, depending upon the amount ofsulfur, the vulcanizing accelerators selected and the ultimatedestination or use of the EPDM composition. That is, when employed as arooftop curable sheet membrane in a warm climate, different acceleratorsand/or amounts thereof will be selected than where the sheet membrane isto be installed in a cooler climate. The amounts of sulfur andvulcanizing accelerators employed in the composition are based on partsper hundred rubber by weight.

                  TABLE I                                                         ______________________________________                                        Cure Package Components                                                                             Broad                                                                         Range    Preferred                                      Ingredients           phr      Range, phr                                     ______________________________________                                        Sulfur                0.25-2.0 0.5-1.5                                        Thiuram accelerators                                                          TMTMS                 0.5-4    1-2                                            TMTDS                 0.5-3.5  1-2                                            TETDS                 0.75-3.5 1-2.5                                          Thiazole accelerators                                                         Captax-MBT            0.25-3   0.35-2                                         Altax-MBTS            0.25-3   0.35-2.5                                       Sulfenamide accelerators                                                      N-cyclohexyl-2-benzothiazole sulfenamide                                                            0.5-3.5  1-2.5                                          N-tert-butyl-2-benzothiazole sulfenamide                                                            0.5-3.5  1-2.5                                          Dithiocarbamate accelerators                                                  Copper dimethyldithiocarbamate                                                                      0.5-3.0  1-2.5                                          Dimethylcyclohexyl-ammonium dibutyl                                                                  0.5-2.75                                                                              1-2.5                                          dithiocarbamate                                                               Tellurium diethyldithiocarbamate                                                                    0.5-2.5  1-2                                            ______________________________________                                    

It is to be understood that the cure package comprises sulfur and atleast one or more of the foregoing accelerators and thus, the amountspresented in Table I are those wherein one or more of the aboveaccelerators are present. As noted hereinabove, the roof sheetingcompound is not cured prior to application and needed not be curedsubsequent thereto. The presence of the cure package allows the sheetmaterial to cure at temperatures of at least about 50° C., readilyobtainable when exposed to sunlight in most climates.

Optional ingredients include, for example, other elastomers (e.g., butylelastomer, neutralized sulfonated EPDM, neutralized sulfonated butyl) inplace of minor amounts of the EPDM, secondary inorganic fillers (e.g.,talc, mica, clay, silicates, whiting) with total secondary fillercontent usually ranging from about 10 to about 150 phr, and conventionalamounts of other rubber compounding additives, such as zinc oxide,stearic acid, antioxidants, antiozonants, flame retardants, and thelike.

The compounding ingredients can be admixed, utilizing an internal mixer(such as a Banbury mixer), an extruder, and/or a two-roll mill, or othermixers suitable for forming a viscous relatively uniform admixture. Whenutilizing a type B Banbury internal mixer, in a preferred mode, the dryor powdery materials such as carbon black are added first followed bythe liquid process oil and finally the polymer (this type of mixing canbe referred to as an upside-down mixing technique).

The resulting admixture is sheeted to thickness ranging from 5 to 200mils, preferably from 35 to 60 mils, by conventional sheeting methods,for example, milling, calendering or extrusion. Preferably, theadmixture is sheeted to at least 40 gauge (0.040 inches) which is theminimum thickness specified in standards set by the Roofing Council ofthe Rubber Manufacturers Association for non-reinforced black EPDMrubber sheets for use in roofing applications. In many cases, theadmixture is sheeted to 40-45 gauge thickness since this is thethickness for a large percentage of "single-ply" roofing membranes usedcommercially. The sheeting can be cut to desired length and widthdimensions at this time.

The method of the present invention is practiced by utilizing an EPDM orEPR sheet material as described herein. As the sheet is unrolled overthe roof substructure in an otherwise conventional fashion, the seams ofadjacent sheet layers are overlapped. The width of the seam can varydepending on the requirements specified by the architect, buildingcontractor or roofing contractor and thus, do not constitute alimitation of the present invention. Generally, seam overlap ranges fromabout a minimum of one inch to as wide as four to six inches. Scrimreinforcement of the rooftop curable heat seamable sheet is optional.

Assuming an overlap of several inches, the next step is to apply heatand some pressure to the edge area to form the seam. Heat in the form ofhot air can be applied to the seam using either a hand-held heating gunor a mobile hot air automatic welding machine, commonly referred to as aheat welding robot. Both of these devices offer a number of differentheat (hot air) settings. Numerous techniques which utilize pressure canbe used to produce an effective seam as are known to those skilled inthe art. Pressure can vary widely from a minimum of about 3 psi up toabout 60 psi, typically so long as it is adequate to provide anacceptable seam strength.

In order to practice the present invention, several EPDM compounds wereprepared and subjected to both peel and shear adhesion tests, as willnow be set forth in detail. The EPDM polymers selected includedRoyalene® 375; and an experimental EPDM terpolymer EPsyn® DE-249 andcharacterization of the polymers is presented in Table II hereinbelow.

                  TABLE II                                                        ______________________________________                                        Polymer Characterization Study                                                                Royalene ®                                                                         EPsyn ®                                                          375      DE-249                                               ______________________________________                                        ML/4 at 125° C.                                                                          51         56.1                                             Ethylene Content, wt %                                                                          76         71                                               Crystallinity, wt %                                                                             14.6       9.3                                              Tg, °C. (by DSC)                                                                         -50.6      -47.5                                            Tm, °C. (by DSC)                                                                         49.3       38.3                                             Unsaturation, %   2.0        1.7                                              Type of unsaturation                                                                            DCPD.sup.a ENB.sup.b                                        -- Mn              69,500    106,000                                          -- Mw             190,300    332,900                                          -- Mn/-- Mw ratio 2.85       3.14                                             ______________________________________                                         .sup.a dicyclopentadiene                                                      .sup.b 5-ethylidene-2-norbornene                                         

The polymer in Table II, differ from other commercially available EPDM's(i.e., Royalene® 3180, Royalene® 2859, Vistalon® 2200, etc.), in that,they are highly crystalline, high ethylene containing polymers. However,many of the other polymer properties listed above are similar to most ofthe commercially available EPDM terpolymers.

The following examples provide five rooftop curable EPDM roofingmembranes and are submitted for the purpose of further illustrating thenature of the present invention and are not to be considered as alimitation on the scope thereof. Parts shown in the examples are byweight for the rubber hydrocarbon with all other parts being per hundredparts of rubber hydrocarbon (phr) by weight.

                  TABLE III                                                       ______________________________________                                        Rooftop Curable Heat Seamable Black EPDM Membranes                            Compound No. 1       2       3     4     5                                    ______________________________________                                        Royalene ® 375                                                                         100     60      75    75    --                                   EPsyn ® DE-249                                                                         --      --      --    --    100                                  Dowlex ® 2027                                                                          --      40      --    --    --                                   LDPE-132     --      --      25    --    --                                   HDPE-12065   --      --      --    25    --                                   HiStr GPF black, phr                                                                       120     125     125   125   130                                  Sunpar 2280 oil, phr                                                                       75      85      85    85    90                                   Sulfur, phr  1.25    1.0     1.1   1.1   1.25                                 TMTDS, phr.sup.a                                                                           1.0     0.75    0.80  0.75  1.0                                  Captax-MBT, phr.sup.b                                                                      0.35    0.30    0.30  0.30  0.35                                 Santocure NS, phr.sup.c                                                                    1       0.75    0.75  0.75  1.0                                  Sulfads, phr.sup.d                                                                         0.60    0.50    0.50  0.50  0.60                                 Total        299.20  313.30  313.45                                                                              313.40                                                                              324.20                               ______________________________________                                         .sup.a TMTDS: Tetramethylthiuram disulfide                                    .sup.b Captax-MBT: 2Mercaptobenzothiazole                                     .sup.c Santocure NS: Ntert-butyl-2-benzothiazole sulfenamide (TBBS)           .sup.d Sulfads: Dipentamethylene thiuram hexasulfide (DPTH)              

In the examples illustrated in Table III, Compound No. 1 was preparedwith 100 parts by weight of Royalene® 375; Compound No. 5 was preparedwith 100 parts by weight of the experimental terpolymer, EPsyn® DE-249and Compounds 2-4 were prepared with mixtures of Royalene 375® and otherthermoplastic polymers, as noted in the above Table. Each of thecompound examples were prepared utilizing standard rubber mixingtechniques and equipment by mixing together the ingredients listedhereinabove.

In order to evaluate the seamability of these sheet materials of thepresent invention, both peel and shear adhesion results were determinedand reported in the tables appearing hereinbelow. These include: peeladhesion and seam shear strength; tensile properties over increasingperiods of time and, crescent tear. The procedure employed for the peeland shear adhesion tests conducted was as follows:

Detailed Peel and Shear Adhesion Test Procedure

Each of the above rubber compounds was subjected to adhesion testingwhich necessitated the building of test pads comprising 6×6 inch sheetsreinforced by using a fabric reinforcement, according to the followingprocedure:

1. A 10×20-inch two roll mill was utilized to prepare a number of6×6-inch sheets of rubber approximately 40 mils in thickness forbuilding adhesion test pads.

2. In order to reinforce the uncured sheets of rubber, a 6×6-inch sheetof PVC treated polyester scrim (10×10 epi cord construction) wasinserted between two 6×6-inch sheets of rubber.

3. The rubber-scrim assembly was covered with a layer of a Mylar filmand placed in the cavity of a metal curing mold (6×6×0.075-inch).

4. The rubber-scrim assembly was then pressed in a Mylar film for aboutfive minutes at about 149° C.

5. Two of the 6×6-inch scrim reinforced rubber pads were seamed togetherusing a hand-held heating gun (Leister). Approximately 15 to 18 poundsforce was applied by means of a roller such as a standard two-inch widemetal roller. Satisfactory seams (either peel or shear) could be formedusing only 3 to 4 pounds force and the standard two-inch wide metalroller. The seams were allowed to equilibrate for 24 hours beforetesting.

6. A clicker machine with a one-inch wide die was utilized to prepare anumber of test specimens for seam peel (Type B, 90° peel) and shear(Type A, 180° peel) adhesion testing.

7. Testing machine: Model 1130 Instron® Universal Tester--a testingmachine of the constant rate-of-jaw separation type. The machine wasequipped with suitable grips capable of clamping the specimens firmlyand without slippage throughout the tests.

8. The one-inch wide specimens were tested at the rate (both crossheadand chart speed) of two inches per minute using the adhesion test setforth in ASTM D-413 (machine method). Both peel and shear adhesionstrength were determined at room temperature (i.e., 23° C.) as well asoccasionally at 70° and 100° C. Specimens were allowed 15 minutes topreheat prior to testing at elevated temperatures.

9. Adhesion strength is defined as:

peel adhesion strength (lbs/inch)=pounds force x sample width;

shear adhesion strength (lbs/square inch)=pounds force x sample width.

Unaged peel adhesion and shear adhesion tests were conducted, utilizingthe test pads discussed hereinabove, and are reported in Tables IV andV. Crosshead and chart speeds for all adhesion tests were conducted atthe rate of two inches per minute (ipm). Stress-strain properties weremeasure at weekly intervals for a period of eleven consecutive weeks on45 mil flat rubber sheets subjected to 50° C. oven aging (Table VI) and70° C. oven aging (Table VII).

                  TABLE IV                                                        ______________________________________                                        Rooftop Curable Heat Seamable Black EPDM Membranes -                          Peel Adhesion Strength Adhesion Studies                                       Compound No.                                                                            1       2        3     4      5                                     ______________________________________                                        Peel Adhesion at 23° C. - Unaged specimens                             Lbs./inch 48      49       24.5  52.5   56                                    Failure type                                                                            (A)     (A,B)    (A)   (A,B)  (A,B)                                 Peel Adhesion at 70° C. - test specimens                               preheated 15 minutes prior to testing                                         Lbs./inch >3.8    >11.6    >3.4  >3     >2.9                                  Failure type                                                                            (B)     (B)      (B)   (B)    (B)                                   ______________________________________                                         (A) = Weld Failure                                                            (B) = Very slight tearing at the interface, followed by rubber tearing to     the fabric reinforcement and eventually rubber separating from the fabric     reinforcement                                                            

Peel adhesion as shown in Table IV for Compounds 1-5, and seam shearstrength in Table V for Compounds 1-5 were substantially reduced whenthe one-inch wide test samples were tested at elevated temperatures. InTable IV, exceptionally high shear adhesion results were obtained atboth 23° C. and 70° C. by replacing 40 parts of Royalene 375 with Dowlex2027, a copolymer of ethylene and octene. Type of test specimen failurewas essentially the same for all five compounds.

For further testing purposes, three rings were cut from dusted 45 milflat sheets, prepared from Compounds 1-5, that had been hanging in aforced air oven at either 50° or 70° C. From both the unaged (controls)and aged samples, standard ring specimens were cut according to ASTMD-412 (Method B--Cut Ring Specimens removed from flat sheets). The ringspecimens were prepared from flat sheets not less than 0.1 mm nor morethan 3.0 mm in thickness and of a size that would permit cutting thering specimen. Modulus and tensile strength at break and elongation atbreak measurements were obtained using a table model Instron® tester,Model 1130, and the test results were calculated in accordance with ASTMD-412. All ring specimens were allowed to set for 24 hours, followingwhich testing was carried out at 23° C.

                  TABLE V                                                         ______________________________________                                        Rooftop Curable Heat Seamable Black EPDM Membranes -                          Seam Shear Strength Adhesion Studies                                          Compound No                                                                             1       2        3      4     5                                     ______________________________________                                        Seam Shear Strength at 23° C. - Unaged specimens                       Lbs./inch.sup.2                                                                         >65     >116.5   >78    >73.5 >65                                   Failure type                                                                            (C)     (C)      (C)    (C)   (C)                                   Seam Shear Strength at 70° C. - test specimens                         preheated 15 minutes prior to testing                                         Lbs./inch.sup.2                                                                         >27.5   >51.5    34     31    27.5                                  Failure type                                                                            (C)     (C)      (A,C)  (A,C) (A,C)                                 ______________________________________                                         (A) = Weld Failure                                                            (C) = Necking/Breaking  rubber test strip elongated and broke adjacent to     the weld seam                                                            

                  TABLE VI                                                        ______________________________________                                        Rooftop Curable, Heat Seamable Black EPDM Membranes -                         50° C. Oven Aging Study                                                Compound No.   1       2      3     4    5                                    ______________________________________                                        Stress-Strain Properties at 23° C.                                     Unaged Controls                                                               100% Modulus, psi                                                                            300     375    430   --   235                                  300% Modulus, psi                                                                            510     525    --    --   475                                  Tensile at break, psi                                                                        690     630    520   450  620                                  Elongation at break, %                                                                       515     395    165    75  450                                  Aged 7 Days at 50° C.                                                  100% Modulus, psi                                                                            350     410    465   --   265                                  300% Modulus, psi                                                                            710     665    --    --   585                                  Tensile at break, psi                                                                        845     720    530   475  730                                  Elongation at break, %                                                                       450     365    150    70  455                                  Aged 14 Days at 50° C.                                                 100% Modulus, psi                                                                            365     435    505   --   290                                  300% Modulus, psi                                                                            730     725    --    --   625                                  Tensile at break, psi                                                                        885     780    565   535  800                                  Elongation at break, %                                                                       440     360    140    60  470                                  Aged 21 Days at 50° C.                                                 100% Modulus, psi                                                                            380     450    535   --   310                                  300% Modulus, psi                                                                            765     760    --    --   690                                  Tensile at break, psi                                                                        910     815    585   560  815                                  Elongation at break, %                                                                       435     350    135    55  420                                  Aged 28 Days at 50° C.                                                 100% Modulus, psi                                                                            385     455    570   --   330                                  300% Modulus, psi                                                                            830     780    --    --   715                                  Tensile at break, psi                                                                        925     805    605   615  825                                  Elongation at break, %                                                                       395     340    130    50  415                                  Aged 35 Days at 50° C.                                                 100% Modulus, psi                                                                            405     470    585   --   350                                  300% Modulus, psi                                                                            835     805    --    --   725                                  Tensile at break, psi                                                                        925     825    625   630  835                                  Elongation at break, %                                                                       380     320    125    55  405                                  Aged 42 Days at 50° C.                                                 100% Modulus, psi                                                                            410     490    605   --   370                                  300% Modulus, psi                                                                            860     820    --    --   760                                  Tensile at break, psi                                                                        940     835    620   610  855                                  Elongation at break, %                                                                       375     310    115    45  400                                  Aged 49 Days at 50° C.                                                 100% Modulus, psi                                                                            415     500    635   --   380                                  300% Modulus, psi                                                                            875     --     --    --   780                                  Tensile at break, psi                                                                        955     820    645   595  870                                  Elongation at break, %                                                                       370     295    120    45  390                                  Aged 56 Days at 50° C.                                                 100% Modulus, psi                                                                            425     510    650   --   390                                  300% Modulus, psi                                                                            900     --     --    --   795                                  Tensile at break, psi                                                                        965     830    660   615  880                                  Elongation at break, %                                                                       355     290    110    40  390                                  Aged 63 Days at 50° C.                                                 100% Modulus, psi                                                                            415     525    --    --   395                                  300% Modulus, psi                                                                            915     --     --    --   800                                  Tensile at break, psi                                                                        970     840    690   645  825                                  Elongation at break, %                                                                       350     285     90    35  370                                  Aged 70 Days at 50° C.                                                 100% Modulus, psi                                                                            410     555    --    --   400                                  300% Modulus, psi                                                                            925     --     --    --   810                                  Tensile at break, psi                                                                        985     845    725   655  895                                  Elongation at break, %                                                                       350     275     80    35  365                                  Aged 77 Days at 50° C.                                                 100% Modulus, psi                                                                            420     575    --    --   410                                  300% Modulus, psi                                                                            925     --     --    --   820                                  Tensile at break, psi                                                                        990     865    745   670  905                                  Elongation at break, %                                                                       345     265     75    35  360                                  ______________________________________                                    

                  TABLE VII                                                       ______________________________________                                        Rooftop Curable, Heat Seamable Black EPDM Membranes -                         70° C. Oven Aging Study                                                Compound No.  1       2       3     4    5                                    ______________________________________                                        Stress-Strain Properties at 23° C.                                     Unaged Controls                                                               100% Modulus, psi                                                                           300     375     430   --   235                                  300% Modulus, psi                                                                           510     525     --    --   475                                  Tensile at break, psi                                                                       690     630     520   450  620                                  Elongation at break, %                                                                      515     395     165    75  450                                  Aged 7 Days at 70° C.                                                  100% Modulus, psi                                                                           345     430     505   --   285                                  300% Modulus, psi                                                                           735     715     --    --   645                                  Tensile at break, psi                                                                       885     840     600   485  785                                  Elongation at break, %                                                                      435     410     175    70  440                                  Aged 14 Days at 70° C.                                                 100% Modulus, psi                                                                           375     460     525   --   305                                  300% Modulus, psi                                                                           775     745     --    --   670                                  Tensile at break, psi                                                                       915     865     615   525  795                                  Elongation at break, %                                                                      415     405     165    70  420                                  Aged 21 Days at 70° C.                                                 100% Modulus, psi                                                                           395     485     550   --   625                                  300% Modulus, psi                                                                           815     785     --    --   685                                  Tensile at break, psi                                                                       935     885     630   545  815                                  Elongation at break, %                                                                      405     395     160    65  420                                  Aged 28 Days at 70° C.                                                 100% Modulus, psi                                                                           425     510     575   --   335                                  300% Modulus, psi                                                                           835     805     --    --   740                                  Tensile at break, psi                                                                       945     880     645   580  835                                  Elongation at break, %                                                                      400     385     155    60  395                                  Aged 35 Days at 70° C.                                                 100% Modulus, psi                                                                           445     525     605   --   360                                  300% Modulus, psi                                                                           865     835     --    --   770                                  Tensile at break, psi                                                                       980     895     640   610  860                                  Elongation at break, %                                                                      395     355     140    55  385                                  Aged 42 Days at 70° C.                                                 100% Modulus, psi                                                                           460     550     630   --   385                                  300% Modulus, psi                                                                           905     885     --    --   815                                  Tensile at break, psi                                                                       980     930     670   630  895                                  Elongation at break, %                                                                      370     340     120    45  365                                  Aged 49 Days at 70° C.                                                 100% Modulus, psi                                                                           485     580     665   --   410                                  300% Modulus, psi                                                                           945     935     --    --   875                                  Tensile at break, psi                                                                       1005    985     695   665  920                                  Elongation at break, %                                                                      340     325     110    40  330                                  Aged 56 Days at 70° C.                                                 100% Modulus, psi                                                                           515     595     --    --   435                                  300% Modulus, psi                                                                           995     985     --    --   925                                  Tensile at break, psi                                                                       1050    1015    735   685  955                                  Elongation at break, %                                                                      335     315      95    35  315                                  Aged 63 Days at 70° C.                                                 100% Modulus, psi                                                                           510     600     --    --   430                                  300% Modulus, psi                                                                           1000    --      --    --   920                                  Tensile at break, psi                                                                       1045    1005    725   690  950                                  Elongation at break, %                                                                      330     295      85    35  320                                  Aged 70 Days at 70° C.                                                 100% Modulus, psi                                                                           515     610     --    --   435                                  300% Modulus, psi                                                                           1020    --      --    --   925                                  Tensile at break, psi                                                                       1065    1025    755   705  960                                  Elongation at break, %                                                                      325     285      75    35  615                                  Aged 77 Days at 70° C.                                                 100% Modulus, psi                                                                           525     635     --    --   445                                  300% Modulus, psi                                                                           1025    --      --    --   940                                  Tensile at break, psi                                                                       1055    1030    770   720  975                                  Elongation at break, %                                                                      320     270      70    30  315                                  ______________________________________                                    

As can be determined from the data in Tables VI and VII, physicalproperties of the specimens increased with time when subjected to 50°and 70° C. oven aging. After eleven weeks of aging, all five membranecompositions showed cure progressing at 50° C., a temperature readilyobtainable by a black roofing membrane exposed to sunlight in mostclimates.

For purposes of comparison, test slabs of Compounds No. 1-5, compressionmolded for 35 minutes at 149° C., were also subjected to stress-straintesting, the results of which are reported in Table VIII hereinbelow.

                  TABLE VIII                                                      ______________________________________                                        Rooftop Curable, Heat Seamable Black EPDM Membranes -                         70° C. Oven Aging Study                                                Compound No.  1       2      3     4     5                                    ______________________________________                                        Stress-Strain Properties at 23° C.                                     Test Specimens Cured 35' at 149° C.                                    Unaged                                                                        100% Modulus, psi                                                                           360     575    440   500   330                                  300% Modulus, psi                                                                           725     760    730   710   775                                  Tensile at break, psi                                                                       785     775    765   760   875                                  Elongation at break, %                                                                      365     320    335   345   405                                  Crescent tear at 23° C. - Die C -                                      Test Specimens Cured 35' at 149° C.                                    Unaged                                                                        Lbs./inch     183     208    169   195   244                                                195     212    182   166   241                                  Average       189     210      175.5                                                                               180.5                                                                               242.5                              ______________________________________                                    

As can be determined from the data presented in Table VIII, physicalproperties were generally no better than where the membranes had beensubjected to oven aging without pre-cure and, after eleven consecutiveweeks of aging, the oven aged membranes had improved stress-strainproperties over the unaged, compression molded roofing membranes(Compounds 1-5). In other words, the roofing membrane compositions(Compounds 1-5) aged in a forced air oven at either 50° or 70° C.appeared to be fully cured after eleven weeks of aging.

In conclusion, it should be clear from the foregoing examples andspecification disclosure that the use of EPDM, EPR or any other olefintype polymers, having high ethylene content, high crystallinity and highmolecular weight in compositions having a specific cure package whichallows such sheet material to be rooftop curable. After eleven weeks ofaging, all five compounds showed good cure development in both 50° and70° C. forced air ovens, suggesting potential for rooftop curing.Moreover the sheet materials do not require the use of any adhesive forseaming or splicing the overlapping adjacent edges of said sheetmaterials.

It is to be understood that the invention is not limited to the specifictypes of EPDM exemplified herein or by the disclosure of other typicalEPDM, EPR or other olefin type polymers provided herein, the exampleshaving been provided merely to demonstrate the practice of the subjectinvention. Those skilled in the art may readily select other EPDM, EPRor other similar olefin polymers including copolymers of ethylene andbutene as well as ethylene and octene, according to the disclosure madehereinabove. Similarly, the invention is not necessarily limited to theparticular fillers, the curatives or the processing material exemplifiedor the amounts thereof.

Thus, it is believed that any of the variables disclosed herein canreadily be determined and controlled without departing from the scope ofthe invention herein disclosed and described. Moreover, the scope of theinvention shall include all modifications and variations that fallwithin the scope of the attached claims.

What is claimed is:
 1. A single-ply rooftop curable heat seamable sheetmaterial for roofing prepared from an uncured polymeric composition ofmatter comprising:100 parts by weight of a curable semi-crystallinepolymer having more than about 2 percent by weight crystallinity andselected from the group consisting of polyolefins prepared from monomerscontaining at least 2 carbon atoms, said polymer having an ethylenecontent of at least about 60 percent; from about 20 to 300 parts byweight of a filler selected from the group consisting of reinforcing andnon-reinforcing materials and mixtures thereof per 100 parts of saidpolymer; from about 20 to 150 parts by weight of a processing materialor mixtures thereof, per 100 parts of said polymer; and from about 1.5to 10 parts by weight of a sulfur cure package having at least onevulcanizing accelerator, said cure package capable of allowing saidcomposition of matter to cure at temperatures of from about 50° C. toabout 68° C.
 2. A rooftop curable heat seamable sheet material, as setforth in claim 1, wherein said polymer comprises a terpolymer ofethylene, propylene and a diene monomer having an ethylene content of 75percent by weight, a weight average molecular weight of about 190,000and about 14.6 percent by weight crystallinity.
 3. A rooftop curableheat seamable sheet material, as set forth in claim 2, wherein saidfiller comprises about 120 parts by weight of carbon black and saidprocessing material comprises about 75 parts by weight of processingoil, per 100 parts by weight of said polymer.
 4. A rooftop curable heatseamable sheet material, as set forth in claim 2, wherein said curepackage comprises from about 0.25 to 2 parts by weight of sulfur; fromabout 1 to 4 parts by weight of at least one thiuram accelerator; fromabout 0.25 to 2 parts by weight of a thiazole accelerator and, fromabout 1 to 2.5 parts by weight of a sulfenamide accelerator, per 100parts by weight of said polymer.
 5. A rooftop curable heat seamablesheet material, as set forth in claim 4, wherein said cure packagecomprises 1.25 parts by weight of sulfur; 1 part by weight of a thiuramaccelerator; 0.5 to 1 parts by weight of a thiazole accelerator and, 1to 2 parts by weight of a sulfenamide accelerator, per 100 parts byweight of said polymer.
 6. A rooftop curable heat seamable sheetmaterial, as set forth in claim 1, wherein said polymer comprises aterpolymer of ethylene, propylene and a diene monomer having an ethylenecontent of 71 percent by weight, a weight average molecular weight ofabout 332,900 and about 9 percent by weight crystallinity.
 7. A rooftopcurable heat seamable sheet material, as set forth in claim 6, whereinsaid filler comprises about 125 parts by weight of carbon black and saidprocessing material comprises about 80 parts by weight of processingoil, per 100 parts by weight of said polymer.
 8. A rooftop curable heatseamable sheet material, as set forth in claim 6, wherein said curepackage comprises from about 0.25 to 2 parts by weight of sulfur; fromabout 1 to 4 parts by weight of at least one thiuram accelerator; fromabout 0.25 to 2 parts by weight of a thiazole accelerator and, fromabout 1 to 2.5 parts by weight of a sulfenamide accelerator, per 100parts by weight of said polymer.
 9. A rooftop curable heat seamablesheet material, as set forth in claim 8, wherein said cure packagecomprises 1.25 parts by weight of sulfur; 1 part by weight of a thiuramaccelerator; 0.5 to 1 parts by weight of a thiazole accelerator and, 1to 2 parts by weight of a sulfenamide accelerator, per 100 parts byweight of said polymer.